Russian President Vladimir Putin has congratulated Turkish President Recep Tayyip Erdogan on a referendum that will expand his powers, the Kremlin and Turkish state media said on April 18.
The Kremlin said that Putin phoned Erdogan and congratulated him on the "successful conduct" the referendum.
A day earlier, U.S. President Donald Trump congratulated Erdogan on his "victory" in the referendum, which is being challenged by the opposition and has been greeted coolly by the European Union.
Turkish media said Putin and Erdogan emphasized the importance of normalizing ties and maintaining a cease-fire in Syria that was jointly brokered by Ankara and Moscow earlier this year.
The Kremlin said that the cease-fire and Syrian peace talks need to be reinforced.
It also said both sides called for an unprejudiced investigation into the suspected chemical attack in Syria earlier this month that killed more than 80 people.
Ankara accuses President Bashar al-Assad's government of carrying out the attack with the deadly nerve agent sarin.
Russia and Assad's government have alleged government bombs could have hit rebel chemical weapons stocks or that the suspected attack was staged -- claims that the United States and other countries have dismissed.